The active head restraint deployed on it's own. I was stopped at a light and the headrest slammed into the back of my head. I was alone in the vehicle, and nothing struck the seat or my vehicle. Upon inspection, the plastic clips that hold the metal bar in place have broken. It caused a headache and neck pain, as it jarred me unexpectedly. This affected my safety, and had I been moving at the time it could have caused an accident, putting others at risk as well. I called the dealer I purchased the vehicle from and was quoted over $600 for the part (replacement headrest) and labor, but have not taken it in for them to inspect it. There were no claims filed, so no inspections have occurred. There were no warnings, neither lights or messages, or any other problems with any part of the driver's seat. It just exploded.